The Three Types of Chart Junk

A recent posting on Dmitry Fadeyev’s design blog got me thinking about decoration and chart junk again. Fadeyev talks about the Victorian obsession with ornamentation, but he could equally be talking about the way charts and infographics are often decorated. A short excursion to the 1850s might help shed some light on the issue of chart junk.

Product Design in the Victorian Age

Fadeyev uses some illustrations from the catalog of the 1851 Great Exhibition in London, which is available from Google Books. Victorian design was incredibly ornamental and decorated, and that included everyday objects. The Victorian idea of a properly decorated home was that there would be no empty spaces. A bare wall was unthinkable, there had to be something there: a pattern, a mural, anything but a single color.

Fadeyev uses this stove to illustrate the obsession with ornament. Besides the intricacy of the decoration and amount of effort that must have gone into it, it also strikes me as incredibly impractical. I guess part of showing your status was not just the ornaments on the stove, but the matching set of servants that would keep all the little leaves and figurines clean und dust-free.

What caught my eye in particular, though, was this gas lamp. All I could think was, why? Why a guy with a helmet on a lamp? What’s the point? At least in this case, I don’t see the decoration interfering with the function of the lamp. Still, I don’t get it.

The catalog has a few more gems, but what inspired this posting is this set of a “silver fish-carver and fork.”

Fadeyev points out the way the decorations are not just added on here, but are woven into the functional parts of the object. But more than that, the decoration actually interferes with that function. Look at the fork’s tines and the way they point outward: this doesn’t look like it actually works very well. Also, things will easily get stuck in the little hooks at the bases of the tines. The knife has a similar problem, though it may not matter so much depending on how much the design on its blade sticks out.

Back to Chart Junk

The modernist movement that was largely inspired by opposition to Victorian design (and also mass-produced goods that needed to be simpler) might have coined a term for these ornaments: design junk. But even though they did not, they despised any unnecessary flourishes and ornamentation. Decoration is sin.

Tufte defines chart junk as all the parts of a visualization that do not convey data. Junk clutters up charts and can get in the way, but is often harmless. In contrast to ornaments on objects, chart junk can also help the user understand the data by providing context, though.

So the way I see it, there are three types of chart junk:

Useful junk. This includes all the parts of a graphic that do not convey data, but that carry useful or interesting context. In an infographic, this is what makes the infographic work. In a visualization, this may be annotations, explanatory text, etc.

Harmless junk. This includes parts of a visualization or infographic that do not convey data and also don’t help understanding, but also don’t get in the way. If you add a pretty picture next to the chart that doesn’t interfere, or if you insist on an elaborate border around it. A lot of chart junk falls into this category.

Harmful junk. The kind of chart junk that actively interferes with reading and understanding of a visualization or infographic. This includes elaborate graphics that hide the true end of a bar, busy background images, etc.

Next time you see an infographic or a visualization that includes seemingly extraneous elements, ask yourself: is this the guy with helmet on the gas lamp (harmless), or is it the fork with the outward-pointing tines (harmful)? Or, perhaps, is the junk even useful?

Robert Kosara is Senior Research Scientist at Tableau Software, and formerly Associate Professor of Computer Science. His research focus is the communication of data using visualization. In addition to blogging, Robert also runs and tweets. Read More…

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Comments

There’s also the question of visual material that is present not to convey the content but to make it memorable, to fix the image in the memory. Frances Yates’s book The Art of Memory has some very useful stuff on this from the pont of view of an academic historian of ideas.

For an example of “useful junk” take a look at the graph here which discusses the child mortality in India. In this case I would not even refer to it as junk. It forms an essential core of the graphic.

Look at page 59 of Tufte’s The Visual Display of Quantitative Information. The decorations around this chart match those of the Victorian era. I don’t consider these decorations to be chartjunk since they are not part of the graph itself and do not interfere with the data. If anything, they call attention to it. I consider a pretty picture next to a chart or an elaborate border around a chart to be similar to Tufte’s decorations. They may add context or alter the mood but are not chartjunk since they are not part of the chart itself.